JComboBox custom editor and model

Question

I'd like to implement a custom JComboBox that uses application's arbitrary text field as its editor. Below is a first trial but it is dead on birth. Specifically, two action listeners for the text field do not work let alone do accumulating edited items on the combo box. What could be my foolish errors?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import javax.swing.plaf.metal.MetalComboBoxEditor;
public class EditableComboBox extends JComboBox{
  Vector<String> items;
  CustomComboBoxModel model;
  JTextField tfield;
  CustomComboBoxEditor editor;
  public EditableComboBox(Vector<String> vec, JTextField tf){
    items = vec;
    model = new CustomComboBoxModel(items);
    setModel(model);
    tfield = tf;
    editor = new CustomComboBoxEditor(tfield);
    setEditor(editor);
    setEditable(true);
    tfield.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent e){
        handleEditedItem();
  void handleEditedItem(){
    String s = tfield.getText();
    if (s.length() > 0 && ! model.hasElement(s)){
      model.addElement(s); // add new element
  class CustomComboBoxModel extends DefaultComboBoxModel{
    public CustomComboBoxModel(Vector<String> vec){
      super(vec);
    // like to add it to head, not to tail
    public void addElement(Object o){
      insertElementAt(o, 0);
    public boolean hasElement(Object o){
      int size = getSize();
      int idx = getIndexOf(o);
      return (idx > -1 && idx < size);
  class CustomComboBoxEditor extends MetalComboBoxEditor{
    JTextField tfield;
    public CustomComboBoxEditor(JTextField t){
      tfield = t;
    public JTextField createEditorComponent(){
      return tfield;
  public static void main(String[] args){
    final JTextField jtf = new JTextField(80);
    Vector<String> vs = new Vector<String>();
    EditableComboBox ecb = new EditableComboBox(vs, jtf);
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add(ecb, BorderLayout.NORTH);
    jtf.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent e){
        System.out.println(jtf.getText());
    frame.pack();
    frame.setVisible(true);
}Edited by: hiwa on Sep 28, 2007 3:08 PM

Answer 1

This is the final or provisional production version based on Michael's first solution. I find the class is much more useful when the handleEditedItem() method can be called from the application because the application can control the behavior.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
public class JTextFieldWithMemory extends JComboBox{
  Vector<String> items;
  CustomComboBoxModel model;
  JTextField tfield;
  int columns;
  /* constructor for a special usage, this obj calls handleEditedElement() */
  public JTextFieldWithMemory(Vector<String> vec, int cs, boolean handleEdit){
    items = vec;
    columns = cs;
    model = new CustomComboBoxModel(items);
    setModel(model);
    setEditable(true);
    tfield = (JTextField)getEditor().getEditorComponent();
    if (cs > 0){
      tfield.setColumns(columns);
    if (handleEdit){ // automatic self accumulation
      tfield.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
          handleEditedItem();
  /* ordinary usage constructor, application calls handleEditedElement() */
  public JTextFieldWithMemory(Vector<String> vec, int cs){
    this(vec, cs, false);
  public JTextFieldWithMemory(Vector<String> vec){
    this(vec, 0);
  public JTextFieldWithMemory(){
    this(new Vector<String>(), 0);
  public JTextField getTextField(){
    return tfield;
  public String getText(){
    return tfield.getText();
  public void setText(String t){
    tfield.setText(t);
    handleEditedItem();
  public Vector<String> getItems(){
    return items;
  public void addActionListenerTf(ActionListener al){
    tfield.addActionListener(al);
  public void handleEditedItem(){
    String s = tfield.getText();
    if (s.length() > 0 && ! model.hasElement(s)){
      model.addElement(s); // add new element
    tfield.setText(s); // prevent blanking out
  class CustomComboBoxModel extends DefaultComboBoxModel{
    public CustomComboBoxModel(Vector<String> vec){
      super(vec);
    // like to add it to head, not to tail
    public void addElement(Object o){
      insertElementAt(o, 0);
    public boolean hasElement(Object o){
      int size = getSize();
      int idx = getIndexOf(o);
      return (idx > -1 && idx < size);
  /* main() for test */
  static JTextField jtf;
  static JTextFieldWithMemory tm;
  public static void main(String[] args){
    Vector<String> vs = new Vector<String>();
    tm = new JTextFieldWithMemory(vs, 30);
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add(tm, BorderLayout.NORTH);
    jtf = (JTextField)tm.getEditor().getEditorComponent();
    jtf.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent e){
        tm.handleEditedItem(); // called from app
        System.out.println(jtf.getText());
    frame.pack();
    frame.setVisible(true);
}